KR100961694B1 - Rework Flow Method After Forming TFT Array Substrate Before Conducting Cell Process - Google Patents

Abstract

The present invention relates to a method for treating long-term air products after completion of a thin film transistor and before a cell process. On top of the thin film transistor substrate on which the thin film transistor is formed, a protective film made of an organic or inorganic insulating material is formed. Occurs. At this time, organic substances and impurities may be formed on the surface of the protective layer, and UV (ultra-violet) light treatment is performed on the protective layer to remove these organic substances and impurities, and impurities may be removed without damaging the protective layer. Therefore, it is possible not only to carry out a more stable manufacturing process in a later cell process, but also to manufacture an improved liquid crystal display device.

Organic protective film, UV (ultra-violet) light treatment, long-term atmospheric, rework flow, benzocyclobutene (BCB)

Description

Rework Flow Method After Forming TFT Array Substrate Before Conducting Cell Process}             

1 is an exploded perspective view illustrating a general color liquid crystal display device;

2 is a block diagram sequentially illustrating a manufacturing process of a liquid crystal display device;

3 is a block diagram specifically illustrating the alignment film forming process of FIG. 2;

4 is a view showing a general alignment film forming method using an alignment film coating apparatus,

5 is a block diagram showing a step of forming a thin film transistor substrate and forming an alignment layer;

FIG. 6 is a block diagram illustrating a process of forming a thin film transistor substrate and forming an alignment layer according to the present invention, in which an inorganic material is used as a protective film.

FIG. 7 is a block diagram illustrating a process of forming a thin film transistor substrate and forming an alignment layer according to the present invention, in which an organic material is used as a protective film.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of treating an array substrate on which a thin film transistor (TFT) is formed in a liquid crystal display device, and in particular, an array substrate performs a cell process in a clean room. The present invention relates to a method of processing an array substrate when waiting.

Recently, the necessity of a flat panel display having excellent characteristics such as thinning, light weight, and low power consumption has emerged in the information age, and thus a liquid crystal display (liquid crystal display), which is particularly excellent in resolution, color display, and image quality, has emerged. Has been developed and is actively applied to laptop computers, desktop monitors, and the like.

A liquid crystal display device has a lower array substrate having a pixel electrode on one surface and an upper substrate having a common electrode on one surface thereof, and the liquid crystal is disposed therebetween with these electrodes arranged to face each other. Configure by filling. The filled liquid crystal has optical anisotropy and polarization, and is driven by a change in electric field generated when a voltage is applied to two electrodes facing each other. That is, since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal. Accordingly, the liquid crystal display device is an apparatus for displaying an image through light transmittance that varies accordingly.

Accordingly, if the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular arrangement direction of the liquid crystal due to optical anisotropy to express image information.

Currently, an active matrix liquid crystal display (AM-LCD) in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner is attracting the most attention due to its excellent resolution and ability to implement video.

In general, the structure of a liquid crystal panel, which is a basic component of a liquid crystal display, has a configuration as shown in FIG. 1.

1 is an exploded perspective view showing a general color liquid crystal display device.

As shown in the drawing, a typical liquid crystal display 11 includes a color filter 17 including a black matrix 16, an upper substrate 15 having a transparent common electrode 13 formed on the color filter, and a pixel region P. As shown in FIG. ) And a lower substrate 21 having an array wiring including a pixel electrode 19 and a switching element T formed on the pixel region, and a liquid crystal 23 between the upper substrate 15 and the lower substrate 21. Is filled.

The lower substrate 21 may also be referred to as a TFT array substrate, and the thin film transistor T, which is a switching element, is positioned in a matrix type, and passes through a plurality of thin film transistors. ) And data wirings 27 are formed.

In this case, the pixel area P is an area defined by the gate wiring 25 and the data wiring 27 intersecting, and the pixel electrode 19 formed on the pixel area P is mainly formed of a transparent electrode. Configure. In general, the transparent electrode of the pixel electrode 19 uses a transparent conductive metal having relatively high transmittance of light such as indium-tin-oxide (ITO). The liquid crystal display device 11 having such a configuration uses an external natural light or artificial light source for most of the light.

In order to configure each component described in FIG. 1 on the upper substrate or the lower substrate, a plurality of metal films and insulating films are generally formed in a thin film form by using a lithography process, such as a glass substrate. It goes through the process of patterning. In other words, forming a thin film on a glass substrate requires several operations such as deposition, exposure, developing, etching, and cleaning and cleaning. have.

Hereinafter, a manufacturing process of the liquid crystal display device will be described with reference to FIG. 2, which is a block diagram.

The block diagram shown in FIG. 1 is a flowchart illustrating a manufacturing process of a liquid crystal cell after completing a generally applied thin film transistor array substrate. In the st10 step, a lower substrate (or a thin film transistor array substrate) is first prepared. A plurality of thin film transistors (TFTs) are arranged on the lower substrate as switching elements, and pixel electrodes are formed in one-to-one correspondence with the TFTs.

The st20 step is to form an alignment layer on the lower substrate.

The alignment layer formation includes spreading and rubbing of the polymer thin film. The polymer thin film is generally referred to as an alignment layer, and should be deposited with a uniform thickness over the entire lower plate, and rubbing should be uniform.

The rubbing is a main process of determining the initial alignment direction of the liquid crystal. The rubbing of the alignment layer enables normal driving of the liquid crystal and has uniform display characteristics. The rubbing process refers to rubbing the alignment layer in a predetermined direction using a cloth, and the liquid crystal molecules are aligned according to a rubbing direction.

In general, a polyimide series, which is an organic alignment layer of an organic series, is mainly used for the alignment layer.

The st30 step represents a process of printing a seal pattern.

The seal pattern in the liquid crystal cell has two functions of forming a gap for liquid crystal injection and preventing leaking of the injected liquid crystal. The seal pattern is a step of uniformly forming a thermosetting resin in a desired pattern, and screen printing has become mainstream.

The st40 step represents a process of applying a spacer.

In the manufacturing process of the liquid crystal cell, a spacer having a constant size is used to precisely and uniformly maintain a gap between the upper substrate and the lower substrate. Therefore, the spacer should be dispersed at a uniform density with respect to the lower substrate at the time of dispersion, and the dispersion method can be largely divided into a wet dispersion method in which a spacer is mixed with an alcohol and sprayed and a dry dispersion method in which only the spacer is dispersed. In addition, dry dispersion is divided into electrostatic dispersion type using static electricity and antistatic dispersion type using gas pressure. In the liquid crystal cell having a structure susceptible to static electricity, many electrostatic dispersion methods are used.

After the diffusion process of the spacer, as shown in the st50 step, the bonding process of the upper plate of the color filter substrate and the lower plate of the thin film transistor array substrate is performed.

The joining arrangement of the top plate and the bottom plate is determined by the margin given at the time of designing each substrate, and a precision of several μm is usually required. If the two substrates are out of the bonding error range, light leaks out, and thus the desired image quality characteristics cannot be expected when the liquid crystal cell is driven.

The st60 step is a step of cutting the liquid crystal cell manufactured in the st10 to st50 step into a unit cell. In general, a liquid crystal cell undergoes a process of forming a plurality of liquid crystal cells on a large area glass substrate and then separating them into a single liquid crystal cell, which is a cell cutting process.

In the initial manufacturing process of the liquid crystal display device, a process of cutting liquid crystals into cells after cutting them into cells at the same time is performed. However, as cell sizes increase, the liquid crystal is injected after cutting into unit cells.

The cell cutting process includes a scribe process of forming a cutting line on the surface of a substrate using a diamond pen having a hardness higher than that of a glass substrate, and a break process of applying a force to cut.

The st70 step is a step of injecting liquid crystal into the liquid crystal cell cut into each unit cell.

The unit liquid crystal cell has a gap of several μm in an area of several hundred cm ² . Therefore, the vacuum injection method using the pressure difference between the inside and outside of the cell is most widely used as a method of effectively injecting liquid crystal into a cell having such a structure.

In the st20 forming / processing step described in FIG. 2, the organic alignment layer is subjected to a rubbing process after forming and curing an organic polymer layer on a substrate by a rotation coating method or a printing coating method. The rubbing process serves to give an alignment direction to the liquid crystal molecules by defining an alignment angle on the surface of the alignment layer. Hereinafter, the alignment film forming / processing step will be described in detail with reference to FIG. 3.

FIG. 3 is a detailed view of the alignment film forming / processing step st20 of FIG. 2. As shown, the alignment film forming process can be largely divided into three steps. First, a step of forming an alignment layer by applying an alignment material to a substrate (st22), and second, curing (st24) at a predetermined temperature to give strength to the alignment layer. Third, by performing a rubbing treatment on the surface of the cured alignment film, an alignment film having a fine alignment direction can be completed (ST3).

Hereinafter, a conventional method of forming an alignment layer will be described in detail with reference to the accompanying drawings. 4 is a diagram illustrating a general alignment film forming method using an alignment film coating apparatus.

As shown in the drawing, in the general method of coating the alignment layer on the glass substrate 30 using a plurality of interlocking rolls, a doctor roll 31, anilox roll 33, Printing equipment consisting of a printing roll 35 and a rubber sheet 37 is used. Of the plurality of rolls, the doctor roll 31 meshes with the anilox roll 33 and the printing roll 35 is configured to mesh with the anilox roll 33. As shown in the figure, a fine groove 33a is formed on the side surface of the anilox roll 33.

In addition, a rubber plate (print mask) 37 having an arbitrary pattern is attached to one surface of the printing roll 35. The pattern of the rubber plate 37 allows the alignment layer to be printed on a portion of the surface of the array substrate except for a portion to which an adhesive is applied and a portion to form a pad.

Looking at the method of forming the alignment layer on the glass substrate using a printing device having the configuration as described above in detail as follows.

First, the glass substrate 30 is fixed to an arbitrary fixing means 32. Next, any alignment material is sprayed onto the anilox roll 33 in the above-described configuration. As described above, when a printing apparatus composed of a plurality of rolls is operated, the doctor roll 31 rotates in contact with the anilox roll 33 and receives the alignment material sprayed on the anilox roll 33. It is deposited in the fine groove (33a) of the anilox roll 33, the alignment material deposited in the anilox roll 33 continuously is the anilox roll 33 and the printing roll 35 It is transferred again to the rubber plate 37 of the said printing roll 35 by rotating. Next, as the alignment material transferred to the rubber plate, as the printing roll 35 rotates, the alignment layer 40 is formed on the substrate 30 in the pattern of the rubber plate 37.

At this time, the pattern of the rubber plate 37 varies in size depending on the model (size of the liquid crystal panel) of the liquid crystal display device to be manufactured. Therefore, the alignment layer 40 may be configured on the substrate 30 in various forms.

Next, a process of curing the alignment film 40 formed on the substrate 30 at a predetermined temperature is performed, and a process of rubbing the surface of the cured alignment film 40 using the rubbing roll 50 is performed. .                         

An alignment layer may be formed on the glass substrate by the method described above.

However, there is a time interval between the formation of the thin film transistor substrate (st10 of FIG. 2) and the printing step (st22 of FIG. 3) for forming the alignment layer, and the thin film transistor substrate is a clean room until the alignment layer is formed. Long waits occur in This will be described with reference to FIG. 5.

FIG. 5 is a block diagram illustrating a step of forming a thin film transistor substrate and forming an alignment layer. First, a gate wiring (25 of FIG. 1) is formed on a transparent substrate such as a glass substrate (st11). At this time, the gate electrode of the thin film transistor is also formed at the same time.

The st12 step is a step of forming a thin film transistor (T in FIG. 1), and refers to a step of forming an insulating film, an active layer, a source / drain electrode, and the like. When the source / drain electrodes are formed, data wiring (27 in FIG. 1) is also formed.

The st13 step is to form a pixel electrode (19 in FIG. 1). The pixel electrode is connected to the thin film transistor and is formed in the pixel region (P in FIG. 1).

Next, in the st14 step, a protective film is formed on the entire surface of the substrate on which the thin film transistor and the pixel electrode are formed. As the protective film, silicon nitride (SiN _X ), which is an inorganic insulating material, or benzocyclobutene (BCB), which is an organic insulating material, is used.

As described above, the thin film transistor substrate is subjected to a process of waiting in a clean room until the thin film transistor substrate is completed and the alignment layer is formed (st15). Depending on the progress of the cell process, the thin film transistor substrate has a time interval of 10 to 20 days or more waiting for the next process. At this time, even if the thin film transistor substrate is located in a clean room, impurities such as an organic film, an oxide film, or other fine particles may be formed on the surface of the protective film. Such impurities impair the printability of the alignment layer (polyimide) significantly when forming the alignment layer as shown in FIGS. 3 and 4 and cause defects during the process.

Therefore, it is necessary to remove these impurities as in the next step, st16. Such impurities are subjected to a strip treatment with a material such as IPA (isopropyl alcohol) or an ashing treatment with a dry asher. That is, impurities are removed from the surface of the protective film by stripping and post-ash stripping in the st16 step of FIG.

Such an impurity removal process serves to increase the printability of the alignment film when the alignment film is printed in the next step st22.

However, when BCB, an organic material, is used as a protective film, ashing may cause severe damage to the BCB film, thereby preventing ashing, and inorganic silicon nitride (SiN _X ) may be protected. Even if used as a long-term air of more than 20 days has been causing a problem that the ashing (plasma) to be subjected to the ashing (plasma) before the strip (strip) treatment.

Therefore, in order to solve the above problems, the present invention is to remove the organic matter or impurities formed on the top of the thin film transistor substrate using UV (ultra-violet) light. In addition, in the case of a BCB protective film that is difficult to ashing treatment, impurities can be removed without damaging the BCB protective film through UV treatment.

According to an aspect of the present invention, there is provided a method of treating a long-term air product after completion of a thin film transistor according to the present invention, including: forming a thin film transistor on an upper portion of a substrate; Forming a pixel electrode electrically connected to the thin film transistor; Forming a protective layer on the thin film transistor and the pixel electrode; Storing the substrate on which the protective layer is formed in a clean room; Performing ultra-violet (UV) light treatment on the protective layer after storage in the clean room; Performing a strip treatment on the UV light-treated protective layer; And printing an alignment layer on the protective layer after the strip treatment, wherein the integrated illuminance of the UV light is 215 mJ / cm ² or more.

The protective layer is, for example, benzocyclobutene (BCB) as an organic insulating material.

The protective layer may be formed of an inorganic insulating material, for example, the protective layer is characterized in that the inorganic insulating material is silicon nitride (SiN _X ). The strip treatment is characterized in that using isopropyl alcohol (IPA).

In addition, the UV light treatment is characterized in that to remove organic matter and impurities from the protective layer. The thin film transistor may be an inverted stagger type, a stagger type, or a coplanar type.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 6 is a block diagram illustrating a process of forming a thin film transistor substrate and forming an alignment layer according to the present invention, in which an inorganic material is used as a protective film.

The st 111 step shows forming a gate wiring (25 in FIG. 1) on a transparent substrate such as a glass substrate. A conductive material such as a metal is deposited on the glass substrate and patterned to form a plurality of gate wirings extending in the first direction. At this time, the gate electrode of the thin film transistor is also formed at the same time.

The st112 step is to form a thin film transistor (T in FIG. 1). An insulating layer and a semiconductor layer are formed on the entire surface of the substrate on which the gate wiring and the gate electrode are formed, and only the semiconductor layer is patterned to form an active layer. The metal layer is deposited on the entire surface of the substrate and patterned to form source / drain electrodes and data wirings (27 in FIG. 1). The data line extends in the second direction while being substantially perpendicular to the gate line extending in the first direction.

The st113 step is to form a pixel electrode (19 in FIG. 1). A transparent conductive material such as ITO or IZO is formed on the entire surface of the substrate and patterned to form a pixel electrode in the pixel region (P in FIG. 1). The pixel electrode is electrically connected to the thin film transistor.

Next, in the st114 step, an inorganic protective film is formed on the entire surface of the substrate on which the thin film transistor and the pixel electrode are formed. As the inorganic protective film, silicon nitride (SiN _X ), which is an inorganic insulating material, is used.

Through the above process, the thin film transistor substrate is completed. Although the process of forming an inverted stagger type thin film transistor has been described above, the thin film transistor of the present invention is not limited to an inverted stagger type and is a stagger type or a coplanar type ( Thin film transistors such as coplanar type) may also be applied.

As described above, the thin film transistor substrate on which the inorganic protective layer is formed on the substrate on which the thin film transistor and the pixel electrode are formed has a thin film transistor substrate formed earlier in a clean room before the next cell process. Wait for that

The thin film transistor substrate has a waiting time of 20 days or more in a clean room depending on the progress of the cell process of the thin film transistor substrate formed earlier.                     

st 116a shows the treatment of a thin film transistor substrate with a short latency of less than 20 days. The thin film transistor substrate having a short waiting time of less than 20 days can easily remove impurities such as organic substances formed on the surface of the inorganic protective film by stripping alone. Strip treatment uses a material such as IPA (isopropyl alcohol).

On the other hand, st116b represents a processing step of a thin film transistor substrate having a long waiting time of 20 days or more. Long-term air products having a relatively long time of 20 days or more cause a larger amount of impurities such as organic matter to form on the surface of the inorganic protective film than the waiting time of less than 20 days. Even if the thin film transistor substrate is stored in a clean room, the formation of impurities such as organic substances may be reduced, but the formation of impurities may not be completely prevented. For long-term atmospheric products longer than 20 days, the surface of the inorganic protective film is treated with ultra-violet (UV) light, as shown in st116b. UV light has the best performance in removing organic matter and does not cause any damage to the inorganic protective film. In addition, unlike the ashing process of the prior art, it can bring about a simplification of work and an improvement in productivity. At this time, the integrated illuminance of the UV light is 215 mJ / cm ² or more.

After the UV light treatment, the substrate is then stripped in step st117. Strip treatment is the same as in st116 using IPA (isopropyl alcohol).                     

The thin film transistor substrate which has undergone such an impurity removal process (st116a or (st116b + st117)) enters the printing process of the alignment film (st120). Since impurities formed in the inorganic protective layer are removed in the impurity removal process st116a or st116b + st117, the printability of the alignment film is improved. In addition, since the UV treatment of the st116b does not cause any damage to the inorganic protective film, it is possible not only to perform a more stable manufacturing process in a subsequent cell process, but also to manufacture an improved liquid crystal display device. .

FIG. 7 is a block diagram illustrating a process of forming a thin film transistor substrate and forming an alignment layer according to the present invention, in which an organic material is used as a protective film.

In step 211, a gate wiring (25 in FIG. 1) is formed on a transparent substrate such as a glass substrate. A conductive material such as a metal is deposited on the glass substrate and patterned to form a plurality of gate wirings extending in the first direction. At this time, the gate electrode of the thin film transistor is also formed at the same time.

The st212 step is to form a thin film transistor (T in FIG. 1). An insulating layer and a semiconductor layer are formed on the entire surface of the substrate on which the gate wiring and the gate electrode are formed, and only the semiconductor layer is patterned to form an active layer. The metal layer is deposited on the entire surface of the substrate and patterned to form source / drain electrodes and data wirings (27 in FIG. 1). The data line extends in the second direction while being substantially perpendicular to the gate line extending in the first direction.

The st213 step is to form a pixel electrode (19 in FIG. 1). A transparent conductive material such as ITO or IZO is formed on the front surface of the substrate and patterned to form pixel electrodes in the pixel region (P in FIG. 1). The pixel electrode is electrically connected to the thin film transistor.

Next, in the st214 step, an organic passivation layer is formed on the entire surface of the substrate on which the thin film transistor and the pixel electrode are formed. As the organic protective film, benzocyclobutene (BCB), which is an organic insulating material, is used.

Through the above process, the thin film transistor substrate is completed. Although the process of forming an inverted stagger type thin film transistor has been described above, the thin film transistor of the present invention is not limited to an inverted stagger type and is a stagger type or a coplanar type ( Thin film transistors such as coplanar type) may also be applied.

As described above, the thin film transistor substrate on which the organic protective layer is formed on the substrate on which the thin film transistor and the pixel electrode are formed has a thin film transistor substrate formed earlier in a clean room prior to the next cell process. Wait for that

The st 215 step shows the atmospheric process of such a thin film transistor substrate. According to the progress of the cell process of the thin film transistor substrate formed earlier, the thin film transistor substrate waits for a long time in a clean room. However, even if the thin film transistor substrate is in the clean room, the formation of impurities such as organic substances can be reduced. Even if it does not completely prevent the formation of impurities.

UV-ultraviolet (UV) light treatment is performed before the cell process to remove organic substances and impurities formed on the organic protective layer on the top of the substrate. The prior art has caused a number of problems such as damaging the organic protective film during ashing (BC) ashing process. However, if the UV light treatment as in the present invention this problem will disappear. UV light has the best performance in removing organic matter and does not cause any damage to the organic protective film. In addition, unlike the ashing process of the prior art, it can bring about a simplification of work and an improvement in productivity. At this time, the integrated illuminance of the UV light is 215 mJ / cm ² or more.

Next, the st217 step shows a step of stripping the substrate after the UV light treatment. Strip treatment uses a material such as IPA (isopropyl alcohol).

The thin film transistor substrate including the organic passivation layer that has undergone the impurity removal processes st216 and st217 enters the printing process of the alignment layer (st220). Since impurities formed in the organic protective layer are removed in st216 which is an impurity removing step, the printability of the alignment film is improved. In addition, since the UV treatment of the st216 does not cause any damage to the organic protective layer, it is possible not only to perform a more stable manufacturing process in a subsequent cell process, but also to manufacture an improved liquid crystal display device. do.

Therefore, the long-term air treatment according to the present invention has the following effects. When the thin film transistor substrate waits for a cell process, which is the next process for a long time in a clean room, impurities such as organic substances are generated in the protective layer formed on the top of the substrate. UV light treatment is performed. By doing so, no damage may be caused to the protective film formed on the uppermost part of the substrate, and the subsequent stable cell manufacturing process may be performed in the cell process as well as to further improve the liquid crystal display device. do.

Claims (11)

Forming a thin film transistor on the substrate; Forming a pixel electrode electrically connected to the thin film transistor; Forming a protective layer on the thin film transistor and the pixel electrode; Storing the substrate on which the protective layer is formed in a clean room; Performing ultra-violet (UV) light treatment on the protective layer after storage in the clean room; Performing a strip treatment on the UV light-treated protective layer; Printing an alignment layer on the protective layer after the strip treatment; And an integrated illuminance of the UV light is 215 mJ / cm ² or more. delete The method of claim 1, And the protective layer is formed of an organic insulating material. The method of claim 3, wherein The organic insulating material is benzocyclobutene (BCB) array substrate processing method for a liquid crystal display device. The method of claim 1, And the protective layer is formed of an inorganic insulating material. The method of claim 5, The inorganic insulating material is silicon nitride (SiN _X ) array substrate processing method for a liquid crystal display device. The method of claim 1, The UV light treatment is an array substrate processing method for a liquid crystal display device to remove organic substances and impurities on the protective layer. The method of claim 1, And the thin film transistor is an inverted stagger type. The method of claim 1, The thin film transistor is a stagger type (stagger type) array substrate processing method for a liquid crystal display device. The method of claim 1, The thin film transistor is a coplanar type (coplanar type) array substrate processing method for a liquid crystal display device. The method of claim 1, The strip processing is an array substrate processing method for a liquid crystal display using IPA (isopropyl alcohol).

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